The exemplary embodiment relates to the fabrication arts and finds particular application in connection with system and method for fabrication of solid bodies, such as electrodes, by powder consolidation.
Current manufacturing techniques for forming shaped bodies include subtractive shaping, formative shaping, and additive shaping. Subtractive shaping starts with a raw material and then successively subtracts pieces away to achieve the desired morphology and tends to produce large amounts of waste material. Examples of such techniques include grinding, drilling, and machining. Formative shaping applies pressure and often heat to the raw material, generally requiring high energy. Examples of such techniques include pressing, bending, casting, and forging. Additive shaping involves the successive addition of raw material to form a desired product. Three-dimensional (3-D) objects can thus be built from multiple layers of material.
Additive manufacturing offers several benefits over traditional manufacturing methods. These include lower production costs, increased design flexibility, and shorter product development times. Production costs can be reduced by lessening the amount of waste material generated by traditional machining processes, simplifying the production line by using fewer operations, and eliminating the additional investment in tooling and fixtures required for new products. This can be advantageous for small- to medium-scale productions of metal parts, especially in industries with short product life cycles and high innovation demands. However, conventional additive manufacturing techniques entail the use of high energy in the form of laser energy or heat. For example, laser aided additive manufacturing (LAAM) techniques have been developed which use laser energy as a heat source for melting a base substrate while simultaneously adding material in a layer-by-layer process. However, the LAAM process is subject to several limitations including a lack of control over phases and microstructures, potential defects, surface oxidation, and laser-based heat and energy requirements. (Melchior, T., et al., Solar-driven biochar gasification in a particle-flow reactor. Chem. Eng. Process. 48, 1279-1287 (2009); Cannone, A. G., et al., Comments on the evaluation of valve regulated lead-acid batteries (VRLA) under deep cycling regimes. IEEE 13th Ann'l Battery Conf. on Applications and Advances, 271-278 (1998)).
In the battery field, manufacturing of lead (Pb) electrodes traditionally involves high pressure injection of a molten lead alloy into casts, machining grooves into flat lead alloy plates, or crimping and rolling lead strips into rosettes that are inserted into holes in a casted plate. (Reddy, T. B. Linden's Handbook of Batteries, Fourth Edition. (McGraw-Hill 2011). More recently, carbon-based current collectors coated with electroplated Pb have been developed to increase the specific energy density. However, corrosion-induced degradation of the surface coating and stress-induced cracking of the carbon composite during cycling poses significant difficulties. (Kirchev, A., et al. Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept. J. Power Sources 196, 8773-8788 (2011)). Powder consolidation processes, particularly in the manufacture of metal foams, generally involve high temperature sintering or melting. One sintering-dissolution process (SDP) for the production of Al metal foams involves mixing and compacting dry Al and NaCl powders in a mold. The mixture is then sintered far below the melting point of the NaCl and finally the NaCl is dissolved away using deionized water. (Zhao, Y. Y., et al. A novel sintering-dissolution process for manufacturing Al foams. Scripta Materialia 44, 105-110 (2001). A direct foaming process has also been proposed in which a thick slurry, containing a mixture of Al particles and surfactants to prevent agglomeration and stabilize the particles, is poured into molds, dried at atmospheric conditions for consolidation, and the heat treated above the melting point to achieve consolidation. (Barg, S., et al. Novel open cell aluminum foams and their use as reactive support for zeolite crystallization. J. Porous Materials 18, 89-98 (2011)). A hydrothermal bayerite synthesis method has also been developed that involves the growth and consolidation of Al particles by the formation of a porous layer of aluminum hydroxide. The hydroxide formation makes the particles grow in size and acts as a binder to hold the particles together when in contact. (Rat'ko, A. I., et al. Hydrothermal synthesis of porous Al2O3/Al metal ceramics: II. Mechanism of formation of a porous Al(OH)(3)/Al composite. Kinetics and Catalysis 45, 149-155 (2004)).
All of these methods tend to involve high energy/raw material costs or produce unstable products.
The exemplary embodiment provides a method for additive manufacturing which enables shaped bodies to be formed which overcomes the problems with existing methods.